05-03-2013, 02:45 PM
Introduction to Digital Signal Process ORS
Introduction to Digital.ppt (Size: 84 KB / Downloads: 36)
Where DSPs found?
Consumer products
DVD, MP3, HDTV
Communications
Radio, Cellular Phones
Medical
Pacemakers, MRI, Spectrometers
Industrial
Motor controllers, environmental controls
Technologies used for Digital Signal ProcessING
General Purpose Processors (GPP)
Intel IPX400, IBM PowerPC
Field Programmable Gate Array (FPGA)
Xilinx, Altera
Application Specific Integrated Circuit (ASIC)
DSP Processors (or DSPs)
Advantages of DSPs
Reprogrammable
High level to assembly programming with well documented tools
Cost effective in low volume applications
Modestly priced development hardware
Desirable speed / cost / efficiency for evaluation of design trade-offs
Motivations for DSP Architecture
Most features of DSPs have the structures of a DSP algorithm
Fast multipliers
Multiple Execution Units
Efficient Memory access
Data formats
Streamlines I/O
Special instruction sets
The Multiple Execution Unit
High computation complexity requires multiple types of arithmetic and logic to be preformed in parallel to increase speed.
Parallel execution units will have:
MAC
ALU
Shifter
Example: Texas Instruments C6713 DSP
It has 8 execution units ( two sections called .L, .M, .S, .D )
All blocks are multi-function and can add Integers
Only the .M blocks can multiply
.D is mostly used to save and store data
.L mostly does logical operations
.S mostly does shifting
Efficient Memory Access
Technique used to provide greater bandwidth
Use of separate Instruction bus and multiple data buses
Caching of instruction so they don’t consumer bandwidth
Providing L1 and L2 caching for single cycle access
Automatic address generation that is incremented without hardware intervention.
FIFO buffers
Auto increment for arrays access
Delay lines
Zero overhead looping
Special loop instructions or hardware is used to implement “for loops” such that it will automatically
Store and update an increment
Evaluate a conditional
Repeat only a specific number of times
The Special Instruction Set
Special instruction sets are provided for a DSP to maximize hardware use.
Perform parallel operations with single intructions
Include data operations, pointer updates and arithmetic simultaneously
They also can minimize memory space used
Use of smaller instruction word length
Change of Hardware configuration to decrease instructions that are used
Specialized instruction may require coded in assembly due to added complexity
Types of Multi-issue Architecture
VLIW( Very Long Instruction Word) or its hybrid VelocTI (both are TI inventions)
Many execution units each having its own instruction. Four to eight executions to cycle
Instructions and executions are group at the time the program is compile/assembled
Superscalar
Uses special hardware to group instruction and executions in parallel
Extremely complex design and not deterministic (same code many execute in different orders each time its call changing the time taken to perform)